The present invention relates generally to medical plastic formulations and particularly to medical liquid containers such as flexible, collapsible, intravenous solution containers. The materials disclosed exhibit the particular advantages of being essentially transparent, soft and flexible, essentially free of extractables, and able to resist high temperatures present in autoclaving.
Various materials have been utilized for intravenous solution containers in the past. In particular, U.S. Pat. No. 4,140,162 discloses a formulation for medical liquid containers containing both polypropylene and a block copolymer. A third ingredient disclosed comprises polyethylene or polyethylene vinyl actate. The present invention is distinguished from the '162 patent by the use of ethylene methyl acrylate, which is lower in cost and provides more desirable physical properties such as improved thermal stability and a wider range of processing temperatures. Other formulations of block copolymers which include polypropylene may be found in U.S. Pat. No. 3,792,124. These formulations are not suitable for flexible medical liquid containers, however, in that they are ionic, which would alter the solutions contained therein.